In recent years, there has been widespread use of display devices each having an integration of a display section and an input section for reduction in size of the devices. In particular, in the case of portable terminals such as mobile phones, PDAs (personal digital assistants), and laptop personal computers, there has been widespread use of display devices each including a touch panel that is capable of detecting the position of contact between a display surface and a finger or stylus (an object to be detected) brought into contact with the display surface.
There have conventionally been known various types of touch panel such as so-called resistive (pressure-sensitive) touch panels and capacitive touch panels. Among them, capacitive touch panels have been in widespread use.
A capacitive touch panel detects the position of contact between a display surface and a finger or stylus by detecting a change in capacitance that occurred when the finger or stylus was brought into contact with the display surface. This makes it possible to detect the position of contact with a simple operation.
Further, unlike a resistive touch panel, the capacitive touch panel does not require the formation of two electrically conductive films with an air layer sandwiched therebetween, and therefore does not suffer from interface reflection of outside light at the interface between an air layer and an electrically conductive film.
However, the capacitive touch panel, which detects the position of contact by detecting a change in capacitance, might be incapable of correct detection of the position of contact due to a change in line of electric force that is caused by extrinsic noise received by the touch panel.
Touch panels that have conventionally been in widespread use are out-cell or on-cell touch panels (e.g., see Patent Literature 1) that are mounted on the outer sides of display panels.
However, the provision of a touch panel on the outer side of a display panel undesirably causes emission noise to be generated from the display panel when a touch panel operation is carried out while a display is being carried out, so that there is an increase in the amount of noise that is received by the touch panel.
For this reason, the provision of a touch panel on the outer side of a display panel might cause a reduction in SN ratio (signal-to-noise ratio), with the result that the touch panel deteriorates in detection performance and therefore wrongly detects the position of contact.
Further, the provision of a touch panel on the outer side of a display panel undesirably causes the resulting device to increase in thickness and weight due to the stacking of the touch panel on the display panel.
Moreover, the provision of a touch panel on the outer side of a display panel causes outside light to be reflected not only on a surface of the touch panel but also at the interface between the touch panel and the display panel, so that contrast and viewability are adversely affected. Further, the provision of a touch panel on the outer side of a display panel causes viewability to deteriorate due to the touch panel per se.
Under such circumstances, an in-cell touch panel, i.e., a touch panel incorporated in a cell of a display panel or the like, has been under development from the point of view of reduction in thickness and weight, improvement in viewability, and cost advantages, such as reduction in the number of components, which are brought about by making touch panels “in-cell” (e.g., see Patent Literatures 2 and 3).
A typical example of an in-cell touch panel is a structure which constitutes an electro-optic device such as a display panel or a display device and which includes an array substrate such as a TFT (thin-film transistor) substrate, a counter substrate such as a CF (color filter) substrate, and a so-called sensor electrode so fabricated between the array substrate and the counter substrate as to serve as a position detecting electrode for detecting the position of contact with an object.
Patent Literatures 2 and 3 disclose a sensor electrode sandwiched between an insulating substrate of a CF substrate and a transparent counter electrode made of ITO (indium tin oxide), with the CF substrate used as a touch panel substrate (i.e., an in-cell touch panel substrate) to constitute an in-cell touch panel.
FIG. 34 is a cross-sectional view showing a configuration of a display device described in Patent Literature 2, and FIG. 35 is a plan view showing a configuration of a sensor electrode as taken along the line A-B shown in FIG. 34.
As shown in FIG. 34, a display device 300 described in Patent Literature 2 includes a display panel 304, and the display panel 304 includes a TFT substrate 301, a CF substrate 302, and a liquid crystal layer 303 sandwiched between the TFT substrate 301 and the CF substrate 302.
The CF substrate 302 includes an insulating substrate 311, a counter electrode 319 (common electrode), and a CF layer 318 provided between the insulating substrate 311 and the counter electrode 319, and the CF layer 318 is constituted by a light blocking section 316 (BM) and a plurality of colored layers 317 (CF) provided between adjacent parts of the light blocking section 316. The CF substrate 302 further includes a first electrode layer 312 and a second electrode layer 314 provided as a sensor electrode between the CF layer 318 and the insulating layer 311, with an insulating layer 313 provided between the first electrode layer 312 and the second electrode layer 314.
As shown in FIGS. 34 and 35, the first electrode layer 312 has a line portion 312a that extends linearly along a first direction and a bulge portion 312b that bulges from the line portion 312a. Further, the second electrode layer 314 has a line portion 314a that extends linearly along a second direction perpendicular to the first direction and a bulge portion 314b that bulges from the line portion 314a. 
FIG. 36 is a cross-sectional view schematically showing a configuration of a main part of the CF substrate 302, which is used as a touch panel substrate to constitute an in-cell touch panel, of the display device 300 described in Patent Literatures 2 and 3, with the constituent layers stacked in the order shown. It should be noted that FIG. 36 is equivalent to a cross-sectional view schematically showing a configuration of a main part of the CF substrate 302 of the display device 300 shown in FIG. 34.
In Patent Literature 1, as shown in FIG. 34, an insulating layer 320 and a shield electrode 321 are provided between the CF layer 318 and the counter electrode 319. However, the insulating layer 320 and the shield electrode 321 are not illustrated here. Further, although FIG. 36 shows the light blocking section 316 (BM) and the colored layer 317 (CF) as if they are stacked, they are actually provided on substantially the same lamination level (see FIG. 34).
It should be noted that Patent Literatures 2 and 3 disclose that the first electrode layer 312 and the second electrode layer 314 may be made of, for example, a metal patterned into a grid shape (mesh shape), instead of being made of a sheet electronically conductive transparent material.